The present description relates to a power coupling device which can switch a torque transmission state between two coupling members.
There is known a power coupling device which may engage and disengage two rotational coupling members depending on a direction of torque transfer. When a torque transfer between the two coupling members is in one direction, the power coupling device engages the two coupling members and transfers torque from one to the other. When the torque transfer is in the other direction, the power coupling device disengages the two rotational members and permits a freewheeling overrunning motion between the two coupling members.
There is known and presented, for example in U.S. Pat. No. 6,244,965, a two-way overrunning coupling device which controllably takes forward and reverse lock states. When the device takes the forward lock state, a first strut pivoted at its one end on the first coupling member penetrates through a hole of a retainer plate arranged between the first and second coupling members. The relative rotation between the first and second coupling members in one direction is prevented by engaging the first strut with a recess of the second coupling member. But it is permitted in the other direction by the second coupling member running over the first strut.
When the overrunning coupling device takes the reverse lock state, the retainer plate retains the first strut in a pocket of the first coupling member, and instead a second strut pivoted at its end opposite to that of the first strut in the circumferential direction penetrates a hole of the retainer plates. Then, the relative rotation between the first and second coupling members in the other direction is permitted by the second strut running over the first pivot, but it is prevented in the one direction by the second strut engaging with the recess of the second coupling member.
The coupling device of the '965 patents can lock the relative rotation between the first and second coupling members in either of the forward and reverse directions, and a forward lock state and a reverse lock state can be achieved. However, it can not enable a free rotation in the both directions nor a complete engagement between the first and second coupling members.